I just purchased a 2007 Mazda 3 s ATX this past weekend. It has 41000 miles on it and belonged to a single owner who purchased the vehicle. I have very little knowledge of the service history of this vehicle. It simply looks like all the owner did was change the oil, and he never went to the dealership to do it. There are multiple Quicklube type stickers in the dash.

I read in another thread about changing the transmission fluid for the ATX around every 30k miles for this car. I was just trying to get your opinions on what I should do. Should I wait until the fluid looks bad then change it? Or simply change it now, and begin the process of changing it every 30k miles.

I do a lot of highway driving daily on this car. Around 100 miles a day mostly at 60-70 mph so I need to do everything I can to help my car last as long as possible.

I have little confidence in automatic transmissions so my recommendations may be a bit conservative. Just for the sake of full disclosure.

Definitely don't wait until the fluid turns brown or black and/or starts to smell burned. Change it while it still looks OK and has not yet broken down to the point where it may no longer be providing minimum acceptable performance. This is maintenance job, not a repair - the idea is to keep things working properly, not to fix a problem caused by failure to do proper maintenance. Over the life of the car the cost of doing regular ATF changes may equal the cost of replacing a transmission (probably not, but maybe) but not having to deal with the hassle of having a transmission fail makes it much more than a break-even thing.

At 4 years/41,000 miles I would definitely have the filter changed and a proper flush and fill performed. Not just a drain and fill job, which will only change about 3-4 quarts of the ~8 quarts the transmission holds. I also consider a big transmission cooler a virtually mandatory upgrade for any ATX vehicle.

For fluid I would say you are definitely safe to use genuine Mazda brand M5 fluid from the dealer - Mazda is not going to sell junk that will wipe out your transmission. An equally viable option is Motorcraft FNR5 ATF. This fluid meets the same M5 spec as the Mazda fluid which is expected as it is what Ford uses/recommends for the ATX in the Fusion, which uses the Mazda6 power train.

Various other M5 compatible ATFs are available from the regular suspects like Castrol, Mobil, Amsoil, etc and I'm sure they are all fine. Even with my skeptical/conservative views about slushboxes if you install a good trans cooler and go with 30,000 mile change intervals I would say the expense of a synthetic fluid may be overkill, but it certainly will add a little safety margin and/or peace of mind.

[quote author=Athrex link=topic=175902.msg3721915#msg3721915 date=1278611627]
The thing that concerned me is I'm staring at the Mazda service guide I have, and it doesn't even mention transmission fluid which made me shake my head.
[/quote]

Yes, According to the guide, you change it when the dealer says it needs to be changed. No interval. It's kind of dumb, but I think they do it to not take responsibility if something goes wrong.

I did a drain and fill on mine at 30k and it was a brownish pink. I was gonna replace the filter and the dealer told me it doesn't have one, just a pick up screen which doesn't need to be changed. Did they BS me, should my local auto parts store have a filter&amp;gasket kit??? I'm at 45k and was gonna drain and fill again but the fluid was still very clean so i'm gonna wait till my next oil change at 50k to do it. Should I look for a trans filter kit for when i do it??? Also at 50k on my 02' Ford Ranger i changed my spark plugs and did a full cooling system flush and put in a new thermostat for piece of mind. Should I consider doing this on the 3 as well?

They BSed you. For some reason, mazda is telling dealerships to not touch the filter. you can get it an auto parts store. Be wary, however. Some stores carry a part that does not fit correctly. The little sensor that you remove does not go all the way in. I had that problem, with one from carquest. Also, the OEM gasket is a liquid gasket. They do sell the rubber ones too, however. just make sure you avoid cork gaskets.

i had mine done at like 56k when i got it by some stupid local shop, it had never been done before. that's really chancing it lol, almost too high mileage for a first tranny flush. then i found out they fucked up the flush and put in the wrong fluid (dexron III with an additive that makes it Mercon V compatible. Cheap asses... not to mention Mercon V is the wrong shit to put in the car also).

so then i did it myself at like 75k with fully synthetic mobil1 multi vehicle (mazda M-V compatible) ATF and half o'reilley's multi vehicle conventional ATF (M-V compatible). seems to be holding up alright for now..

Hi,
I just got a used Mazda 3 2008 running 60,000 KM and I have been advised by my mechanic that automatic transmission oil needed to be changed as well as the oil filter.
Sadly I couldn't find the original MV Type M4 fluid, I have been told that Toyota T-IV can also work on Mazda 3 transmission, did anyone tried it before on Mazda 3, also if someone know equivalent ATF oil that will make the shits go smoothly. Thanks in advance

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